MOLLUSCA, CEPHALOPODA) Malcolm Dunning

GENERAL PATTERNS IN THE SUMMER DISTRIBUTION OF EARLY JUVENILE OMMASTREPHID SQUID OFF EASTERN AUSTRALIA (MOLLUSCA, CEPHALOPODA) Malcolm Dunning

To cite this version:

Malcolm Dunning. GENERAL PATTERNS IN THE SUMMER DISTRIBUTION OF EARLY JUVE- NILE OMMASTREPHID SQUID OFF EASTERN AUSTRALIA (MOLLUSCA, CEPHALOPODA). Vie et Milieu / Life & Environment, Observatoire Océanologique - Laboratoire Arago, 1985, pp.163- 168. ￿hal-03022060￿

HAL Id: hal-03022060 https://hal.sorbonne-universite.fr/hal-03022060 Submitted on 24 Nov 2020

HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. VIE MILIEU, 1985, 35 (3/4) : 163-168

GENERAL PATTERNS IN THE SUMMER DISTRIBUTION OF EARLY JUVENILE OMMASTREPHID SQUID OFF EASTERN AUSTRALIA (MOLLUSCA, CEPHALOPODA)

Malcolm DUNNING Maritime Estate Management Branch, Quensland National Parks & Wildlife Service, P.O. Box 190, Brisbane North Quay, Queensland 4000 Australia

CEPHALOPODA ABSTRACT. — Larval squid were sampled in three surveys off the eastern Austra-

OMMASTREPHIDAE lian coast in January, March and May 1983. Ommastrephid larvae were abundant and

LARVAL SQUID occurred at over 90 % of stations. Although identification to species level has not so

EASTERN AUSTRALIA far been possible for the majority of spécimens, gênerai patterns of distribution with

DISTRIBUTION respect to latitude and bottom depth are presented.

CEPHALOPODA RÉSUMÉ. — De jeunes Céphalopodes planctoniques ont été échantillonnés au large

OMMASTREPHIDAE de la côte Est de l'Australie en janvier, mars et mai 1983. Les « larves » d'Ommas-

LARVES tréphidés étaient abondantes et présentes dans plus de 90 % des stations. Bien que

AUSTRALIE EST l'identification des spécimens au niveau de l'espèce n'ait pas été possible jusqu'ici,

DISTRIBUTION du moins pour la majorité des individus récoltés, quelques aspects généraux de la distribution des animaux en relation avec la latitude et la profondeur peuvent être dégagés.

species known from the east coast at that time, INTRODUCTION Nototodarus gouldi (McCoy, 1888). Because of the limited size of the collection, géographie and seaso- Eleven species of the commercially important nal distribution patterns could not be described. squid family Ommastrephidae are known to occur The study described here aimed to obtain preli- off the eastern Australian coast (Nesis, 1979; Oku- minary information on the relative abundance of tani, 1980; Lu & Dunning, 1982; Dunning & Brandt, larval ommastrephid squid across the continental 1985; Dunning, In Prep.). While the distribution and shelf and slope off central eastern Australia and to relative abundance of adults are now relatively well assess any changes in relative abundance with lati- known, few studies have been directed at larval and tude and at différent times during the summer. early juvénile stages of thèse species in Australia Because this area is dominated by a western boun- waters. dary current, water mass associations were also Pélagie cephalopods collected by opportunistic expected to be important and detailed hydrographie plankton tows between the southern Great Barrier information was sought. Reef and southeast Tasmania were described by Broad distributional patterns for species groups Allan (1945). Ommastrephid larvae and early juvéni- only are presented here; detailed species distributio- les were outnumbered in the small collection only by nal patterns require identification of small larvae to "Pyrgopsis pacifiais (Issel)" [probably Leachia spp.] lower taxonomic units than has so far been possible and ail were referred to the only ommastrephid with this collection. 164 M. DUNNING

Unless otherwise indicated, standardized values are used throughout this paper. METHODS Sampling was undertaken on each occasion from south to north to counter the possibility of towing in the same water mass in the southward flowing Early juvénile cephalopods were collected during current. On transects at 34°, 32°, 30° and 28°S on the three eight-day surveys undertaken between 28° and January and March surveys, paired day and night 34°S off the eastern Australia coast in January, samples were taken at each of the eight stations March and May 1983 (Fig. 1). Eight sampling during the same 24 hour period. Information on stations were located along transects roughly per- température, salinity, phosphates, nitrates, silicates pendicular to the continental slope at each degree and oxygen along each transect was obtained using of latitude nominally at bottom depths of 50, 100, expendable bathythermographs and a Neil Brown 200, 400, 1 000 and 2 000 mètres and at stations 5 CTD with rosette sampler. and 10 nautical miles east of the 2 000 m station. Concurrent 30 minute surface tows using 500 (j.m Larval ommastrephid squid are characterized by 50 cm paired Bongo nets and double oblique tows the fusion of the tentacles into a proboscis, persis- using a 500 um 1 m bridleless larval tuna net (FAO, ting from hatching to "metamorphosis" at between 1966) were undertaken at each station. Nominal 5 and 10 mm ML. Further identification was un- towing speed was 1.5 m sec"' (3 knots) with oblique dertaken using the following characters : tows to 150 m where bottom depths exceeded 200 m 1) the diameter of the latéral suckers on the probos- and to 10 m above the bottom in shallower water. cis tip; 3 Catches were standardized to numbers per 1 000 m 2) the location and size of light organs on the using Rigosha flowmeter counts from each net. ventral surface of the eyes and intestine; 3) the length of the proboscis relative to mantle length until the commencement of splitting to form the tentacles; 4) the length of the tentacles just prior to splitting relative to longest arm length. Larvae with mantle lengths greater than 4 mm could generally be identified at least to genus using the above characters. However, the vast majority of the spécimens collected during the study were less than 3 mm ML and thèse spécimens have been separated into three major species groups as shown in the following table :

Sucker Proboscis Species included dianieters length

Group 1 > ML Ommastrephes bartrami Ornithoteuthis volatilis Nototodarus hawaiiensis Group 2 > ML Sthenoteuhis spp. Group 3 < ML Eucleotheuthis luminosa Nototodarus gouldi Todaropsis eblanae Todarodes pacificus

Larvae of Todarodes Jîlippovae would fall into Group 3 morphologically but the known distribution of mature adults (Dunning & Brandt, 1985) makes it unlikely that this species is represented in the collections. No spécimens of Hyaloteuthis pelagica (which have light organs présent on the eyes and intestine from 1.5 mm [Harman & Young, 1985, this vol.]) were represented among the spécimens less than 3 mm ML.

Fig. 1. — Study area showing the East Australian Current and the transects along each degree of latitude. AUSTRALIAN JUVENILE OMMASTREPHID SQUID : SUMMER DISTRIBUTION 165

RESULTS Seasonal and latitudinal distribution of larvae

Numerically, ommastrephids were the dominant Océanographie patterns cephalopod larvae represented in the collections and occurred at over 90% of the stations sampled. Throughout the sampling period, the area was Larvae were more abundant in March than in either dominated by the East Australian Current (EAC) January or May with a mean overall catch rate from (Hamon, 1965; Boland & Church, 1981), carrying oblique tows of 15.7 individuals (standard déviation tropical Coral Sea water southward along the off- [SD] 28.5). This compared with 4.3 (SD 6.4) and 7.5 shore edge of the continental shelf to a point between (SD 8.9) respectively in January and May. A similar 31° and 32°S where it turned eastward to form the pattern was évident in surface samples. In January, Tasman Front (Stanton, 1981). During the January the average catch rate was 5.5 individuals (SD 8.4), and March surveys, the EAC was évident at the in March 24.3 (SD 60.9) and in May, 9.2 (SD 13.9). slope as far south as 32° but in May, had moved The highest catch of 450 individuals per 1 000 m3 away from the slope just to the north of 31°S. A was obtained from a surface sample taken at 32°S température profile throught the current at 32°S in in 100 m depth in March. March is shown in figure 2. Anticyclonic warm core Species group 1 overwhelmingly dominated sam- 'eddies' pinched off from the EAC often occur south ples from the first two surveys, comprising more of 32°S but were not encountered during the sam- than 99 % of ail individuals. Ommastrephes bartrami pling period in the area surveyed. and Ornithoteuthis volatilis were represented among the larger larvae and juvéniles collected. By contrast,

153°E 153-30 44% of spécimens caught during the May cruise 0 —_J— . l were from species groups 2 and 3 and larger spéci- 23=^ mens of Ornithoteuthis volatilis and Sthenoteuthis (probably oualaniensis) were positively identified. ~X N>0\ 19 — Représentatives of species group 3 outnumbered >s \ \ \ 17 those of group 2 by approximately 4 : 1 in this - survey.

32°S 13 Mean catches combining ail depth strata for each AA >i\ \N \ A \ n degree of latitude are shown in Table 1. In January, highest mean catches were at 33°S, in March at 32°S

500

Fig. 2. — Température profile through the EAC at 32 °S, Table I. — Mean catches standardized to 1 000 m3 by March 1983. latitude for the 1983 larval surveys.

Latitude Oblique tows Surface tows Total

Surface currents were strongest in ail three sur- January survey veys at the edge of the continental shelf (400-1 000 m 28°S 4.7 3.2 4.0 29°S 5.8 4.6 5.2 bottom depth) and decreased in velocity both sho- 30°S 2.1 1.4 1.7 reward and seaward. Thèse southerly currents as 31°S 2.6 2.0 2.3 1 32°S 5.5 11.0 8.3 measured by ship's drift reached 1.6 m sec" in 33°S 11.2 18.0 14.6 January at 33°S, 2.05 m sec"1 in March at 31°S and 34°S 0.7 2.9 1.8 1 1.35 m sec" in May at 30°S. Between 30° and 32°S, March survey especially during January, surface currents recorded 28°S 5.4 5.3 5.4 at 50 and 100 m depth stations were typically 29°S 13.6 26.6 20.1 1 30°S 28.4 28.6 28.5 northwest to northward at less than 0.5 m sec" . 31°S 18.2 30.3 24.2 32°S 30.3 55.7 43.0 Surface water températures varied by approxima- 33°S - - - tely 6°C from north to south during each survey, 34°S 0.0 0.5 0.2 with the major change at the température front to the May survey south of the EAC at the point where it turned east. 28°S 3.1 4.6 3.9 In March, a change of 4.7 °C was recorded over 1 29°S 10.1 6.5 8.3 nautical mile at the shelf edge at 32°S. The highest 30°S 17.5 21.6 19.6 31°S 15.3 17.5 16.4 température recorded was 26.9 °C at the shelf edge 32°S 3.7 1.1 2.4 at 28°S in March and the lowest, 19.6 °C on the shelf 33°S 1.8 12.7 7.2 34°S 1.5 at 32°S in March. 1.4 1.4 M. DUNNING

and in May at 30°S. Lowest catches in ail surveys were taken at 34°S. For the March survey, size distribution along the latitudinal gradient was examined. Figure 3 A shows a possible indication of larger larvae north of 30°S.

1.0 2.0 3.0 4.0 5.0 Larvae of 1.0 mm ML and less, sizes close to that at hatching for several ommastrephids, occurred i : Lat. 29-S throughout the area from 28° to 33°S during ail surveys. ■llll.lll Il . . _

1.0 2.0 3.0 4.0 5.0 Distribution with respect to bottom depth

Larval abundance with respect to eight bottom depth strata was examined for the March survey.

1.0 2.0 3.0 4.0 5.0 Surface tows

Lat. 31 "S N = 85

F

2.0 3.0 4.0 5.0 r e Lat. 32'S q 50 100 200 400 1000 2000 +5 +10 N = 348 u Naut.Mle. e n o c 28" 29' 30' 31" 32* 1.0 2.0 3.0- 4.0 y Mantle Length ( mm ) Oblique tows

200m 50 100 200 400 1000 2000 +5 +10 N = 261 Naut.Mle. Depth (m)

2.0 3.0 4.0 5.0 F r □ March Day Tows N = 363 400m March Night Tows N = 412 N-221 e q u e n 2.0 3.0 4.0 5.0 c y 2000m N = 66 0.6 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 4.6 5.0

Mantle Length ( mm ) l.l. 1.0 2.0 3.0 4.0 5.0 Fig. 4. — A, Larval abundance in relation to bottom depth, surface and oblique tows, March 1983; B, Size distribu- 2000m + 10 miles tion, day and night oblique tows, March 1983. N = 50

UUL Fig. 3. — A, Size distribution of larvae in relation to 1.0 2.0 3.0 4.0 5.0 latitude, oblique tows, March 1983. B, Size distribution in Mantle Length ( mm ) relation to bottom depth, oblique tows, March 1983. AUSTRALIAN JUVENILE OMMASTREPHID SQUID : SUMMER DISTRIBUTION 167

Figure 4 A shows that although the pattern for each Larval ommastrephids were caught at more sta- transect differs, catches were generally lower in tions and in greater abundance in this study than oblique tows over depths greater .than 2 000 m in reported by Sato (1973), Yamamoto & Hamada contrast to surface tows which sometimes showed (1981) and Matsuda et al. (1972) for waters between higher catches here. Both showed low catches at Taiwan and southern Japan where similar ommas- 50 m stations. trephid species assemblages are présent. Using 2 m A broad spectrum of size classes was présent at nets, Matsuda et al. (1972) collected larvae at 31.5 % ail depth strata examined with no clear relationship of stations sampled. A mean catch from midlayer between size and bottom depth at the sampling tows of approximately 2.9 individuals was obtained 3 station (Fig. 3 B). At stations deeper than 1 000 m and a maximum of 19 per 1 000 m collected compa- and at 100 m, there is a slight indication of a higher red with 14.4 and 450 in this study. proportion of larvae smaller than 1.5 mm ML. In the western Arabian Sea in an area of signifi- cant upwelling, Nesis (1974) obtained ommastrephid larvae (83 % Sthenoteuthis) at less than 54 % of Day — night comparisons stations sampled compared with more than 90 % in this study. The mean catch rate was, however, higher Size distribution of ail spécimens collected during than obtained from eastern Australian waters — 16.6 the day in March versus those caught at night is per 1 000 m3 compared with a maximum of 15.7 for presented in Figure 4 B. The distribution of spéci- oblique samples taken in March 1983. mens caught at night shows a slightly higher pro- Little différence was évident in the size distribu- portion of larger size classes than does that for tion of larvae caught in March either latitudinally or spécimens from day samples suggesting that diffe- across the shelf from 50 m depth to 10 nautical miles rential net avoidance may be occurring. east of the 2 000 m bottom depth contour. Larvae Of the 32 stations from ail surveys where com- close to the expected size at hatching were évident parisons could be made for oblique tows, 14 showed throughout the EAC area in ail surveys. day catches higher than night catches (44 %). Day Significantly more ommastrephid larvae were catches exceeded night catches in 7 of 23 surface tow caught at night than during the day in both surface comparisons (30 %). Day surface tows were less and oblique tows during the January and March successful in January yielding higher catches than surveys. Diel vertical migration is unlikely to be a the comparable night tow on only 9 % of occasions major contributing factor to this différence at sta- compared with 50 % in March. Day tows were not tions in depths of less than 200 m where tows sample undertaken in May. the entire water column. Evidence from other studies Comparisons of mean catches for day and night (Nesis, 1977; Nesis & Nigmatullin, 1979) suggests samples from both the January and March surveys that even in deeper water, larval and early juvénile are shown below : ommastrephids are predominantly found in the upper 200 m. Together with the différence in size composition between day and night samples obser- Survey Oblique Surface ved, thèse data suggest that larval squid even at thèse Day Night Day Night small sizes are able to avoid plankton nets.

January 2.07 5.2 1.3 6.8 Available information on the seasonal and géo- March 15.1 15.5 30.9 (9.9*) 20.5 graphie distribution of juvéniles and mature adults from the région is limited (Dunning & Brandt, 1985) * Mean if catch of 450 individuals taken at the 100 m station is excluded. and provides little corroboration of tentative identi- fications. Mature adults and small juvéniles of Om- mastrephes, Sthenoteuthis oualaniensis, Ornithoteu- this, Hyaloteuthis and Eucleoteuthis together with DISCUSSION mature adults of Nototodarus hawaiiensis and N. gouldi, Sthenoteuthis sp., Todaropsis and Todarodes pacificus have been recorded between 27° and 35°S Ommastrephid squid larvae were abundant and during March and April in previous years and many broadly distributed in East Australian Current appear to have extended spawning seasons in east waters from midsummer to early autumn but were coast waters. The présence of juvénile spécimens in less abundant in shelf and slope waters immediately ail bimonthly trawl samples from off the northwest to the south of the point where the current turns east Australian coast in 1982-83 suggests that the popula- (generally at or about 32°S near the shelf edge). tion of N. hawaiiensis there spawns throughout the Catches, both from surface and oblique tows were year (Dunning, in prep.) and this species may behave higher in March than in either January or May, similarly off the east coast. In a séries of 12 corresponding to times of highest surface water midwater trawl samples taken in late March 1981 in températures and current velocities. waters of from 200 to 800 m bottom depth near 168 M. DUNNING

34°30'S, juvéniles of six gênera were represented in DUNNING M.C. & S.B. BRANDT, 1985. Distribution and life the following abundances : history of deep-water squid of commercial interest from Australia. Aust. J. Mar. Freshw. Res., 36 (3) : 343-359. Ornithoteuthis.... 279 Sthenoteuthis.... 16 Eucleoteuthis 32 Hyaleuthis 2 FAO, 1966. Report of the Second session : FAO Expert Panel for the facilitation of tuna research, Tokyo, 15-21 Ommastrephes.... 24 Todaropsis 1 Aug. 1966. FAO Fish. Rep., 37, 64 p. If thèse gênera are represented in similar relative HAMON B.V., 1965. The East Australian Current, abundances in the 1983 larval samples, it is probable 1960-1964. Deep-Sea Research, 12 : 899-921. that Group 1 is dominated by Ornithoteuthis larvae HARMAN R.T. & R.E. YOUNG, 1985. The early life stages and Group 3 by Eucleoteuthis luminosa although of the Ommastrephidae from Hawaiian waters. Vie et Nototodarus gouldi may be more abundant in shal- Milieu, 35 (3-4) : 211-222. lower shelf waters. Lu C.C. & M.C. DUNNING, 1982. Identification guide to The larval species assemblage présent in the 1983 Australian arrow squid (family Ommastrephidae). Vict. summer catches changes late in the season with an Inst. Mar. Sci. Tech. Rep., 2. increase in relative abundance of species groups MATSUDA S., F. HANAOKA, K. TSUTOMU, T. ASAMI & M. 2 and 3. Combining positive identifications made HAMABE, 1972. Spawning and environmental factors of from the material with the published data on adult Todarodes pacificus in the southwestern waters of Japan. Agr. Forest & Fisher. Council Rept., 57 : 10-30. and juvénile abundance, this change probably re- flects an increase in the abundance of Sthenoteuthis NESIS K.N., 1974. Cephalopod larvae in the western spp., Eucleoteuthis and N. gouldi with group 1 spe- Arabian Sea. Oceanology, 14 (3) : 441-445. cies — Ornithoteuthis, Ommastrephes and perhaps N. NESIS K.N., 1977. Vertical distribution of pelagic cephalo- hawaiiensis — increasing in abundance from January pods. J. Gen. Biol, 38 (4) : 547-557. to March and then decreasing to a similar level in NESIS K.N., 1979. Squid of the family Ommastrephidae in May as in January. Further clarification of species the Australia-New Zealand Région. Tr. Inst. Okeanol. Akad. SSSR, 106 : 140-146. différences in larval abundance awaits identification of the 1983 collections to lower taxonomic levels NESIS K.N. & CH. M. NIGMATULLIN, 1979. The distribution and biology of the gênera Ornithoteuthis Okada, 1927 than has so far been possible. and Hyaloteuthis Gray, 1849 (Cephalopoda, Oegop- sida). Bull. Moscow Soc. Naturalists, Sect. Biol., 84, (1) : 50-63. ACKNOWLEDGEMKNT. — Field work for this research OKUTANI T., 1980. Useful and latent cuttlefish and squids was undertaken as part of the CSIRO Division of of the world. National Coopérative Association of Fisheries Research Living Resources Programme. Squid Processors, Tokyo, 66 p. My attendance at the first CIAC Workshop and SATO K., 1973. Identification and distribution of rhyn- Symposium was supported by a travel grant from the choteuthion larvae in the southwestern waters off CSIRO Science and Industry Endowment Fund. Japan during the summer in 1970. Bull. Shizuoka Pref. Fish. Exp. S ta., 8 : 11-21.

STANTON B.R., 1981. An océanographie survey of the

REFERENCES Tasman Front. N.Z.J. Mar. Freshw. Res., 5 : 289-297. YAMAMOTO K. & H. HAMADA, 1981. Identification of rhynchoteuthion larvae in the southwestern waters of ALLAN J., 1945. Planktonic cephalopod larvae from the Japan and Taiwan during the summer in 1971 (Ce- eastern Australian coast. Rec. Aust. Mus., 21 (6) : phalopoda : Ommastrephidae). Bull. Shizuoka Pref. 317-350. Fish. Exp. Stn., 15 : 9-18.

BOLAND F.M. & J.A. CHURCH, 1981. The East Australian Reçu le 28 août 1985; received August 28, 1985 Current 1978. Deep-Sea Research, 28 : 937-957. Accepté le 7 décembre 1985; accepted December 7, 1985

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